This project will investigate: a) the mechanisms of red cell aging, b) hereditary disorders of red cell metabolism, c) the application of techniques of cell separation to preparation of young red cells for transfusion and the study of other blood cell types. Changes in red cell metabolism with "in vivo" aging will be investigated by studying: a) changes in enzymatic kinetic patterns, b) changes in cellular concentration of intermediate metabolites, c) changes in metabolic pattern in a cell free-system, d) progressive alterations of the cell membrane. Red cell enzyme defects associated with chronic hemolysis (hexokinase, pyruvate-kinase and glucose-6-phosphate dehydrogenase) will be analyzed with regard to molecular structure of the enzymes and their isozyme patterns, in normal cells, and in cells from individuals with hereditary enzymopathies. The application of techniques of cell separation to preparation of younger cells for transfusion into patients with diserythropoietic anemias will be evaluated. Studies will be performed of separation of red cells by density on arabino-galactane and polyxyloxanes and by mechanical means, such as the elutriator centifuge and the IBM-2991 cell washer. The separation of other blood cell types by density will also be investigated. An analysis will be performed of a rapid technique for precise platelets counting and sizing and of its relevance to clinical application.